A saliva ejector is an apparatus which includes a suction line and a saliva ejector tip. The saliva ejector tip is disposable. It is inserted into the patient's mouth for the purpose of drawing away excess fluids through the suction line. In the April 1993 edition of the Journal of the American Dental Association, Watson and Whitehouse published a paper entitled "Possibility of Cross-contamination between Dental Patients by means of the Saliva Ejector". This paper documented that, when a patient closes his or her lips around the saliva ejector tip, a higher vacuum can be temporarily created in the mouth than in the suction line and a back flow of fluid containing oral contaminants into the mouth can occur.
Prior to the study by Watson and Whitehouse it had been felt that disposal and replacement of the saliva ejector tip was sufficient protection for the patient. The study clearly showed the presence of alpha-haemolytic organisms, characteristic of oral flora, in the suction line after use. This raises the possibility of a cross-contamination occurring between patients, and demonstrates the need to re-evaluate sanitation and hygienic practises in dental offices.